Conventionally, as light irradiation devices, there have been known light irradiation devices including a reflective surface with a curved-surface shape and a light source for emitting light (for example, Patent Document 1). Further, wire members have been inserted into the reflective surface, and the light source has been configured to emit light toward such wire members in a circumferential direction of the wire members. Further, as light irradiation devices, there have been also known light irradiation devices including a plurality of light sources for emitting light toward wire members introduced in the devices (for example, Patent Document 2).